The Uncertainty Relation

Franz Schwabl

Xiao Zheng, Shao‐Qiang Ma, Guo‐Feng Zhang +2 more

We unify the product and the sum form variance-based uncertainties to a Schr\{o}dinger-liked uncertainty relation. Some well-known uncertainties in either product or sum form can be recovered by the Schr\{o}dinger-liked uncertainty, i.e., the product form uncertainty is the Schr\{o}dinger-liked uncertainty relation for Hermitian operators and the sum form uncertainty is actually Schr\{o}dinger-liked uncertainty relation for non-Hermitian operators. Thus the Schr\{o}dinger-liked uncertainty relation provides a unified uncertainty relation. Also, the unified uncertainty reveals some quantum properties that the traditional uncertainty relation cannot do, and indicates that the uncertainty relation for the incompatible observables is bounded not only by the commutation relation between themselves, but also by the quantities related with the other operator, which is named as auxiliary operator. The importance of the unified uncertainty, as well as the concept of the auxiliary operator deduced from it, is demonstrated in explaining and fixing the trivial lower bound appearing in the traditional uncertainty relations.

Harris Varghese, M. Ravendranadhan

The Robertson's formulation of the uncertainty relation is the most widely accepted form of the Heisenberg uncertainty relation (HUR). It gets modified when we consider it for entangled particles. But this formulation does not consider the measurement process itself. There are reformulation of the uncertainty relations called the generalized uncertainty relations by including the measurement process into the uncertainty relation. HUR gets modified for the case of entangled particles. Here it is shown that the limit of the Generalized Uncertainty Relation (GUR) also reduces for entangled particles. So, GUR also shows similar trend as that of the HUR for entangled particles. Also as entanglement increases, the uncertainty reduces and measurement becomes more precise.

Franz Schwabl

Iwo Białynicki‐Birula, Adam Prystupiuk

This work completes the program started by I. Bialynicki-Birula and Z. Bialynicka-Birula [Uncertainty relation for photons, Phys. Rev. Lett. 108, 140401 (2012); Heisenberg uncertainty relation for photons, Phys. Rev. A 86, 022118 (2012); Heisenberg uncertainty relation for relativistic electrons, New J. Phys. 21, 073036 (2019)] to derive the Heisenberg uncertainty relation for relativistic particles. Sharp uncertainty relations for massive relativistic particles with spin 0 and spin 1 are derived. The main conclusion is that the uncertainty relations for relativistic bosons are markedly different from those for relativistic fermions. The uncertainty relations for bosons are based on the energy density. It is shown that the uncertainty relations based on the time component of the four-current, as we have done previously for electrons, are untenable because they lead to contradictions.